Reservoir tank for vehicle brake system

ABSTRACT

A reservoir tank has an inlet/outlet port communicating with a master cylinder, and a hydraulic fluid supply port provided directly opposite the inlet/outlet port. A tubular portion is provided on the inner surface of the tank. The tubular portion has an internal passage communicating with the inlet/outlet port and having a top opening. A box-shaped member has its bottom plate fitted on the tubular member. The bottom plate is formed of a filter material. A deflector plate is supported on legs extending upwardly form the bottom plate of the box member so as to be disposed right over the top opening of the tubular portion. The deflector plate deflects the flow of hydraulic fluid such that it will not be directed toward the hydraulic fluid supply port, thereby preventing hydraulic fluid from being blown out through the hydraulic fluid supply port even if this port is open.

BACKGROUND OF THE INVENTION

This invention relates to a reservoir tank which is structured to bemounted on a master cylinder or a hydraulic pressure booster in avehicle brake system.

FIG. 10 shows a conventional reservoir tank of this type which isdisclosed in unexamined JP patent publication 10-35469. This reservoirtank, generally designated 110, comprises a tank body 111 made of asynthetic resin, and mounted on a master cylinder 1 with its ports 112and 114 connected to corresponding ports of the master cylinder 1. Thebody 111 has a hydraulic fluid supply port 113 in its top through whichhydraulic fluid a is supplied into the tank 110. Through the ports 112,hydraulic fluid flows between the reservoir and the master cylinder.Through the ports 114, hydraulic fluid a is supplied to the mastercylinder 1 and/or hydraulic units such as pumps. Numeral 115 adesignates a strainer.

JP patent publication 06-156254 discloses a similar reservoir tank ofwhich the interior is divided into a first fluid chamber and a secondfluid chamber, with the inlet/outlet port 112 and the hydraulic fluidsupply port 113 communicating with the first fluid chamber and theoutlet ports 114 communicating with the second fluid chamber.

Because this type of reservoir tank is installed in a narrow, limitedspace in a vehicle engine room, its mounting position is limited. Thatis, in most cases, it has to be mounted with the hydraulic fluid supplyport 113 facing upward.

Component parts of this type of vehicle brake system have to befrequently replaced or removed for repair. After such replacement orrepair, air has to be expelled from the brake system. This is done bypumping the brake pedal with the cap 115 of the hydraulic fluid supplyport 113 removed to mount a brake fluid injector or a brake fluid can onthe reservoir tank 110.

When pumping the brake pedal, hydraulic fluid a tends to gush into thereservoir tank through the inlet/out let port 112. As shown, the ports112 and 113 directly face each other. Thus, hydraulic fluid rushing intothe reservoir tank tends to be blown out through the port 113. Hydraulicfluid blown out through the port 113 may find its way into an operator'seye or stain clothes. This causes deterioration in the work environmentand health hazard.

An object of the invention is to provide a reservoir tank having meansfor preventing hydraulic fluid from being blown out through thehydraulic fluid supply port even when this port is open.

SUMMARY OF THE INVENTION

To achieve this object, a deflector is provided in the reservoir tank atsuch a position that hydraulic fluid discharged into the reservoir tankthrough the inlet/outlet port is deflected by the deflector in such away that hydraulic fluid will not be directed toward the hydraulic fluidsupply port.

Specifically, there is provided a reservoir tank for use in a vehiclebrake system including a master cylinder and/or a hydraulic pressurebooster, the reservoir tank comprising a tank body having a fluidchamber therein and formed with an inlet/outlet port adapted to bebrought into communication with the master cylinder or the hydraulicpressure booster, and a hydraulic fluid supply port, the inlet/outletport communicating with the hydraulic fluid supply port through thefluid chamber, and being oriented such that any hydraulic fluiddischarged through the inlet/outlet port into the fluid chamber isdirected toward the hydraulic fluid supply port, the reservoir tankincluding a deflector provided in the fluid chamber for deflectinghydraulic fluid discharged through the inlet/outlet port into the fluidchamber so as not to be directed toward the hydraulic fluid supply port.

A preferable deflector is a deflector plate positioned and sized suchthat hydraulic fluid discharged through the port into the fluid chamberhits against the deflector plate and is deflected so as not to bedirected toward the hydraulic fluid supply port. In one arrangement, anupwardly extending tubular portion is provided on the inner surface ofthe tank body. The tubular portion has an internal passage communicatingwith the inlet/outlet port and having a top opening. The internalpassage serves as an extension of the inlet/outlet port. The reservoirtank further includes a plate member fitted on the tubular portion. Thedeflector plate is supported on a leg member protruding upwardly fromthe plate member so as to be spaced from and facing the top opening ofthe tubular portion.

With this arrangement, simply by fitting the plate member on the tubularportion, the deflector plate can be positioned properly.

Preferably, the fluid chamber is divided into a first fluid chamber anda second fluid chamber by a partitioning wall and the plate member, andthe plate member is made of a filter material so that hydraulic fluidcan flow between the first fluid chamber and the second fluid chamberthrough the plate member. In this case, the hydraulic fluid supply portis provided so as to communicate with the first fluid chamber, and thetank body is further formed with an outlet port communicating with thesecond fluid chamber for supplying hydraulic fluid in the second fluidchamber to the master cylinder and/or other external hydraulic units.

With this arrangement, since the deflector plate and the filter arepreassembled, they can be made smaller in size and manufactured at alower than when they are prepared separately from each other.Preferably, the plate member is a bottom wall of a box-shaped membersupported by the partitioning wall because such a box-shaped member canbe more easily supported by the partitioning wall.

Another preferable deflector comprises a cylindrical member extendingupwardly from the inner surface of the tank body and having an internalpassage communicating with the inlet/outlet port, and a deflector platefitted in the cylindrical member, the deflector plate being formed withholes along the outer circumference thereof, whereby hydraulic fluiddischarged through the inlet/outlet port is deflected laterally byhitting against the central portion of the deflector plate, and flowsthrough the holes out of the cylindrical member. Still anotherpreferable deflector is a deflector plate supported on a leg protrudingfrom an inner surface of the tank body, the deflector plate having asurface facing the inlet-outlet port.

Yet another preferable deflector is a tubular member provided on theinner surface of the tank body, the tubular member having an internalpassage communicating with the inlet/outlet port and having an openingcommunicating with fluid chamber, the opening being oriented such thathydraulic fluid discharged through the opening will not be directedtoward the hydraulic fluid supply port.

The deflector prevents hydraulic fluid discharged into the reservoirtank through the inlet/outlet port from being blown out through thehydraulic fluid supply port even if the hydraulic fluid supply port isopen. This prevents deterioration in the work environment and healthhazard.

Thus, the reservoir tank can be mounted in an optimum position in anarrow, limited space in a vehicle engine room.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and objects of the present invention will become apparentfrom the following description made with reference to the accompanyingdrawings, in which:

FIG. 1 is a partially cutaway front view of an embodiment of the presentinvention;

FIG. 2 is a partially cutaway plan view of the same;

FIG. 3 is a partially cutaway perspective view of an element of thesame;

FIG. 4 is a partially cutaway front view of another embodiment;

FIG. 5 is a partial perspective view of the embodiment of FIG. 4;

FIGS. 6-9 are partially cutaway front views of other embodiments; and

FIG. 10 is a partially cutaway front view of a conventional reservoirtank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiment of FIGS. 1-3 is a reservoir tank 10 in a vehicle brakesystem for controlling brake hydraulic pressure. The reservoir tank 10includes a tank body 11 formed of a synthetic resin and mounted on amaster cylinder 1 with its ports 12 and 14 connected to correspondingports of the master cylinder 1. A partitioning wall 18 is provided inthe tank body 11. (Throughout the drawings, not the entire partitioningwall 18 is shown.) The partitioning wall 18 prevents pulsation ofhydraulic fluid a. As shown in FIGS. 1 and 2, an open-topped box-shapedmember 20 (see FIG. 3) is supported by the partitioning wall 18. The boxmember 20 has a bottom plate 21. The partitioning wall 18 and the bottomplate 21 of the box member 20 divide the interior of the tank 10 into afirst fluid chamber 16 and a second fluid chamber 17. The tank 10 isformed with a hydraulic fluid supply port 13 communicating with thefirst fluid chamber 16. The outlet ports 14, through which hydraulicfluid a is supplied to the master cylinder 1 and/or hydraulic elementssuch as a pump, communicate with the second fluid chamber 17.

The inlet/outlet port 12, through which hydraulic fluid a flows betweenthe master cylinder 1 and the reservoir tank 10, is formed in a bottomwall 11 a of the tank body 11. The tank body 11 has a tubular portion 19extending from the bottom wall 11 a to the bottom plate 21 of the boxmember 20, with its top end inserted in a hole 21 a formed in the bottomplate 21. The tubular portion 19 has an internal passage communicatingat its bottom end with the port 12 and at its top end with the firstfluid chamber 16. Thus, the port 12 communicates with the first fluidchamber 16 through internal passage of the tubular portion 19. Exceptthe area where the hole 21 a is formed, the bottom plate 20 is a filter22. Hydraulic fluid a from the master cylinder 1 thus flows through theport 12 into the first fluid chamber 16 and then flows through thefilter 22, where fine debris such as rubber pieces and fine powders areremoved, into the second fluid chamber 17. The thus filtered hydraulicfluid a is then supplied to various hydraulic elements.

Right over the hole 21 a, a deflector means or plate 24 is supported bytwo legs 23 extending vertically from the edge of the hole 12 a. Thedeflector plate 24 deflects hydraulic fluid a blown upwardly into thefirst fluid chamber 16 through the hole 21 a in lateral directions asshown by arrows in FIG. 1. The port 12, the hole 21 a and the hydraulicfluid supply port 13 are substantially aligned with each other as shownin FIG. 1. Thus, without the deflector plate 24, during bleeding of airafter replacement of brake parts, if hydraulic fluid a rushes into thefirst fluid chamber 16 through the hole 21 a, it may partially blow outthrough the port 13. The deflector plate 24 will deflect the flow ofhydraulic fluid and thus prevent hydraulic fluid from being blown outthrough the port 13. The number of legs 23 is not limited unless theynoticeably interfere with the flow of hydraulic fluid a.

In the embodiment of FIGS. 4 and 5, a cylindrical portion 31 is formedon the inner surface of the bottom wall 11 a of the tank body 11 aroundthe inner opening 12 a of the inlet/outlet port 12. A cylindrical member32 having a bottom plate 24 as a deflector plate is received in thecylindrical portion 31. The deflector plate 24 is formed with aplurality of holes 33. Any hydraulic fluid a rushing through the port 12into the cylindrical portion 31 hits against the central portion of theplate 24, is deflected laterally, and passes through the holes 33 (seearrows in FIG. 4). By the time the hydraulic fluid passes through theholes 33, its flow speed will slow down significantly, so that it willnever blow out through the port 13. The number and positions of theholes 33 are determined such that the deflector plate 24 cansufficiently deflect the flow of hydraulic fluid but will not undulyinterfere with the flow of hydraulic fluid. Otherwise, they are notlimited.

FIGS. 6-9 show embodiments having different deflector means. Thedeflector means in the embodiment of FIG. 6 is a deflector plate 24supported on legs 41 extending upwardly from the bottom wall 11 a of thetank body 11 around the port 12 so as to be disposed right over the port12. Hydraulic fluid a rushing into the tank through the port 12 hitsagainst the deflector plate 24 and is deflected as shown by arrows.

The deflector means in either of the embodiments of FIGS. 7 and 8 is atubular member 42 formed on the inner surface of the bottom wall 11 a ofthe tank body 11 so as to surround the port 12. The tubular member 42has an opening 42 a oriented such that hydraulic fluid a blown outthrough the opening 42 a will not be directed toward the hydraulic fluidsupply port 13. For example, the opening 42 a is oriented toward theside wall 11 b of the tank body 11. The tubular member 42 in theembodiment of FIG. 7 is an integral part of the tank body 11. Thetubular member 42 in the embodiment of FIG. 8 is a separate member fromthe tank body 11 and is pressed into and/or bonded to a flange formedaround the port 12 as shown, or bonded or otherwise fixed to the bottomwall 11 a around the port 12.

In the embodiment of FIG. 9, a deflector member 24 having an L-shapedsection hangs from the top wall 11 c of the tank body 11 in which isformed the hydraulic fluid supply port 13. The deflector member 24includes a horizontal plate 24 a. A substantially vertically extendingauxiliary deflector plate 24 b may be provided on the underside of thehorizontal plate 24 a as shown by phantom line. If the plate 24 b isprovided, the portion of the horizontal plate 24 a hidden by the plate24 b as viewed from the port 12 is not necessary and thus is omitted.The area and position of the horizontal plate 24 a and/or the verticalplate 24 b are determined such that any hydraulic fluid blown throughthe port 12 toward the port 13 hits against the horizontal plate 24 a or24 b and is deflected, and such that the plates 24 a and 24 b will notunduly interfere with the flow of hydraulic fluid. Otherwise, theirareas and positions are not limited.

The concept of the present invention is applicable to both a reservoirof which the interior is divided into the first fluid chamber 16 and thesecond fluid chamber 17 by the filter 22 and the partitioning wall 18 asshown in FIGS. 1-3 and a reservoir of which the interior is notpartitioned at all. The deflector means may be provided not only at theport 12 but also at one or both of the ports 14. Further, the concept ofthis invention is also applicable to a reservoir tank for a hydraulicpressure booster.

1. A reservoir tank for use in a vehicle brake system including a mastercylinder and/or a hydraulic pressure booster, said reservoir tankcomprising a tank body having a fluid chamber therein and formed with aninlet/outlet port adapted to be brought into communication with themaster cylinder or the hydraulic pressure booster, and a hydraulic fluidsupply port, said inlet/outlet port communicating with said hydraulicfluid supply port through said fluid chamber, and being oriented suchthat any hydraulic fluid passing through said inlet/outlet port towardsaid fluid chamber is directed toward said hydraulic fluid supply port,said reservoir tank including a deflector provided in said fluid chamberfor deflecting hydraulic fluid discharged from said inlet/outlet port sothat a major portion of the hydraulic fluid passing through theinlet/outlet port toward the hydraulic fluid supply port is deflected bythe deflector so as not to be directed toward said hydraulic fluidsupply port; wherein said deflector is a deflector plate positioned andsized such that hydraulic fluid discharged through said inlet/outletport hits against said deflector plate and is deflected so as not to bedirected toward said hydraulic fluid supply port, the hydraulic fluidwhich hits against said deflector being deflected by the deflectorbefore the hydraulic fluid enters said fluid chamber; an upwardlyextending tubular portion provided on the inner surface of said tankbody, said tubular portion having an internal passage communicating withsaid inlet/outlet port and having a top opening, said internal passageserving as an extension of said inlet/outlet port so that hydraulicfluid passing through said inlet/outlet port enters the internal passagebefore entering the fluid chamber, said reservoir tank further includinga plate member fitted on said tubular portion, said deflector platebeing supported on a leg member protruding upwardly from said platemember so as to be spaced from and facing said top opening of saidtubular portion; and wherein said fluid chamber is divided into a firstfluid chamber and a second fluid chamber by a partitioning wall and saidplate member, and wherein said plate member is made of a filtermaterial, whereby hydraulic fluid can flow between said first fluidchamber and said second fluid chamber through said plate member, saidhydraulic fluid supply port communicating with said first fluid chamber,said tank body being further formed with an outlet port communicatingwith said second fluid chamber for supplying hydraulic fluid in saidsecond fluid chamber to the master cylinder and/or other externalhydraulic units.
 2. The reservoir tank of claim 1 wherein said platemember is a bottom wall of a box-shaped member supported by saidpartitioning wall.
 3. A reservoir tank for use in a vehicle brake systemincluding a master cylinder and/or a hydraulic pressure booster, saidreservoir tank comprising a tank body having a fluid chamber therein andformed with an inlet/outlet port adapted to be brought intocommunication with the master cylinder or the hydraulic pressurebooster, and a hydraulic fluid supply port, said inlet/outlet portcommunicating with said hydraulic fluid supply port through said fluidchamber, and being oriented such that at least a portion of an imaginarycontinuation of the inlet/outlet port passes through the hydraulic fluidsupply port, said reservoir tank including a deflector provided in saidfluid chamber for deflecting hydraulic fluid discharged from saidinlet/outlet port so that a major portion of the hydraulic fluid passingthrough the inlet/outlet port toward the hydraulic fluid supply port isdeflected by the deflector so as not to be directed toward saidhydraulic fluid supply port, said imaginary continuation of theinlet/outlet port passing through the deflector; wherein said deflectoris a deflector plate positioned and sized such that hydraulic fluiddischarged through said inlet/outlet port hits against said deflectorplate and is deflected so as not to be directed toward said hydraulicfluid supply port, the hydraulic fluid which hits against said deflectorbeing deflected by the deflector before the hydraulic fluid enters saidfluid chamber; an upwardly extending tubular portion provided on aninner surface of said tank body, said tubular portion having an internalpassage communicating with said inlet/outlet port and having a topopening, said internal passage serving as an extension of saidinlet/outlet port so that hydraulic fluid passing through saidinlet/outlet port enters the internal passage before entering the fluidchamber, said reservoir tank further including a plate member fitted onsaid tubular portion, said deflector plate being supported on a legmember protruding upwardly from said plate member so as to be spacedfrom and facing said top opening of said tubular portion; and whereinsaid fluid chamber is divided into a first fluid chamber and a secondfluid chamber by a partitioning wall and said plate member, and whereinsaid plate member is made of a filter material, whereby hydraulic fluidcan flow between said first fluid chamber and said second fluid chamberthrough said plate member, said hydraulic fluid supply portcommunicating with said first fluid chamber, said tank body beingfurther formed with an outlet port communicating with said second fluidchamber for supplying hydraulic fluid in said second fluid chamber tothe master cylinder and/or other external hydraulic units.
 4. Thereservoir tank of claim 3 wherein said plate member is a bottom wall ofa box-shaped member supported by said partitioning wall.